"Invalid clnors in this fan" warning
The problem is due to custom normals. "clnors" means "Custom Loops Normals".

The meshes have custom normals which means that their normals have been set (instead of auto calculated). When you join several meshes and/or remove doubles this custom setup cannot be maintained.

On each mesh you should do the following (before of after joining them):


Use the "clear custom normals" button (in the geometry data panel)
Remove doubles
Set smooth
Uncheck 'auto smooth'